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dc.contributor.authorPrice, R C
dc.contributor.authorMargison, Geoffrey P
dc.contributor.authorHendry, Jolyon H
dc.contributor.authorWest, Catharine M L
dc.date.accessioned2010-04-26T14:09:29Z
dc.date.available2010-04-26T14:09:29Z
dc.date.issued1995-03
dc.identifier.citationRelationships between the cytotoxic effects of restriction endonucleases and radiation on mammalian cells. 1995, 67 (3):327-34 Int. J. Radiat. Biol.en
dc.identifier.issn0955-3002
dc.identifier.pmid7897281
dc.identifier.urihttp://hdl.handle.net/10541/97414
dc.description.abstractWild-type Chinese hamster ovary (CHO) cells, a radiosensitive mutant CHO line (xrs6), and two human cervical carcinoma cell lines, MS751 and ME180, differ in sensitivity to ionizing radiation with surviving fractions at 2 Gy (SF2) of 0.84, 0.06, 0.90 and 0.24 respectively. Restriction endonucleases (REs) were introduced into the cells by treatment with streptolysin O (SLO) and the effects of this on clonogenic cell survival were compared. A comparison was made of REs inducing either blunt- (AluI) or cohesive-ended (Sau3AI) double-strand breaks. Whilst MS751 cells were resistant to the effects of both REs, AluI caused significantly greater cell killing than Sau3AI in the other three lines (p < 0.05 for all). Both ME180 and xrs6 were significantly more sensitive to REs than their radioresistant counterparts, MS751 and CHO (p < 0.05 for both). In order to investigate the effect of DNA methylation on dsb induction, the isoschizomers MspI and HpaII (cohesive-ended dsb inducers) were introduced into the cell lines. Both REs recognize the same sequence but HpaII cannot cleave if the internal cytosine is methylated. MS751 was also resistant to the effects of both of these enzymes and MspI was more cytotoxic than HpaII in the other three lines (p < 0.03 for all). The differential sensitivity to the two REs was more marked in the radiosensitive cell lines, suggesting that there may be a greater degree of DNA methylation in radiosensitive cells. The variation in sensitivities to REs between the cell lines could not be explained in terms of differences in cell poration following SLO treatment because, although MS751 was resistant to SLO (25% of cells porated), the other three lines showed the same level of cell poration (98% of cells). With these four cell lines, there was a significant correlation between sensitivity to RE and radiosensitivity for AluI, Sau3AI and MspI but not for HpaII.
dc.language.isoenen
dc.subjectCultured Tumour Cellsen
dc.subject.meshAnimals
dc.subject.meshBacterial Proteins
dc.subject.meshCHO Cells
dc.subject.meshCell Survival
dc.subject.meshCricetinae
dc.subject.meshCricetulus
dc.subject.meshDNA
dc.subject.meshDNA Damage
dc.subject.meshDNA Restriction Enzymes
dc.subject.meshFlow Cytometry
dc.subject.meshHumans
dc.subject.meshMethylation
dc.subject.meshRadiation Tolerance
dc.subject.meshStreptolysins
dc.subject.meshTumor Cells, Cultured
dc.titleRelationships between the cytotoxic effects of restriction endonucleases and radiation on mammalian cells.en
dc.typeArticleen
dc.contributor.departmentCancer Research Campaign Department of Experimental Radiation Oncology, Paterson Institute for Cancer Research, Manchester, UK.en
dc.identifier.journalInternational Journal of Radiation Biologyen
html.description.abstractWild-type Chinese hamster ovary (CHO) cells, a radiosensitive mutant CHO line (xrs6), and two human cervical carcinoma cell lines, MS751 and ME180, differ in sensitivity to ionizing radiation with surviving fractions at 2 Gy (SF2) of 0.84, 0.06, 0.90 and 0.24 respectively. Restriction endonucleases (REs) were introduced into the cells by treatment with streptolysin O (SLO) and the effects of this on clonogenic cell survival were compared. A comparison was made of REs inducing either blunt- (AluI) or cohesive-ended (Sau3AI) double-strand breaks. Whilst MS751 cells were resistant to the effects of both REs, AluI caused significantly greater cell killing than Sau3AI in the other three lines (p < 0.05 for all). Both ME180 and xrs6 were significantly more sensitive to REs than their radioresistant counterparts, MS751 and CHO (p < 0.05 for both). In order to investigate the effect of DNA methylation on dsb induction, the isoschizomers MspI and HpaII (cohesive-ended dsb inducers) were introduced into the cell lines. Both REs recognize the same sequence but HpaII cannot cleave if the internal cytosine is methylated. MS751 was also resistant to the effects of both of these enzymes and MspI was more cytotoxic than HpaII in the other three lines (p < 0.03 for all). The differential sensitivity to the two REs was more marked in the radiosensitive cell lines, suggesting that there may be a greater degree of DNA methylation in radiosensitive cells. The variation in sensitivities to REs between the cell lines could not be explained in terms of differences in cell poration following SLO treatment because, although MS751 was resistant to SLO (25% of cells porated), the other three lines showed the same level of cell poration (98% of cells). With these four cell lines, there was a significant correlation between sensitivity to RE and radiosensitivity for AluI, Sau3AI and MspI but not for HpaII.


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